This section is intended to introduce the reader to various aspects of art that may be related to various aspects of the present invention, which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
As will be appreciated, oil and natural gas have a profound effect on modern economies and societies. In order to meet the demand for such natural resources, numerous companies invest significant amounts of time and money in searching for and extracting oil, natural gas, and other subterranean resources from the earth. Particularly, once a desired resource is discovered below the surface of the earth, drilling and production systems are employed to access and extract the resource. These systems can be located onshore or offshore depending on the location of a desired resource. Further, such systems generally include a wellhead assembly through which the resource is extracted. These wellhead assemblies generally include a wide variety of components and/or conduits, such as a Christmas tree (tree), various control lines, casings, valves, and the like, that control drilling and/or extraction operations.
Subsea manifolds such as trees (sometimes called Christmas trees) are well known in the art of oil and gas wells, and generally comprise an assembly of pipes, valves and fittings installed in a wellhead after completion of drilling and installation of the production tubing to control the flow of oil and gas from the well. Subsea trees typically have at least two bores one of which communicates with the production tubing (the production bore), and the other of which communicates with the annulus (the annulus bore).
Typical designs of conventional trees may have a side outlet (a production wing branch) to the production bore closed by a production wing valve for removal of production fluids from the production bore. The annulus bore also typically has an annulus wing branch with a respective annulus wing valve. The top of the production bore and the top of the annulus bore are usually capped by a tree cap which typically seals off the various bores in the tree, and provides hydraulic channels for operation of the various valves in the tree by means of intervention equipment, or remotely from an offshore installation.
Wells and trees are often active for a long time, and wells from a decade ago may still be in use today. However, technology has progressed a great deal during this time, for example, subsea processing of fluids is now desirable. Such processing can involve adding chemicals, separating water and sand from the hydrocarbons, etc.
Conventional treatment methods involve conveying the fluids over long distances for remote treatment, and some methods and apparatus include localized treatment of well fluids, by using pumps to boost the flow rates of the well fluids, chemical dosing apparatus, flow meters and other types of treatment apparatus.
One problem with locating the treatment apparatus locally on the tree is that the treatment apparatus can be bulky and can obstruct the bore of the well. Therefore, intervention operations requiring access to the wellbore can require removal of the treatment apparatus before access to the well can be gained.